(AP) -- In what might embarrass less adventurous souls, astronaut Koichi Wakata is returning to Earth with the underwear he kept on for a solid month during his space station stay and scientists will check them out.
They're experimental high-tech undies, designed in Japan to be odor free.
The Japanese spaceman described his underwear test Thursday as shuttle Endeavour and its crew aimed for a touchdown the next morning. The astronauts released some mini satellites, their final job before Friday's re-entry, and said it was time to come home after more than two weeks aloft.
Wakata has been off the planet for 4 1/2 months.
"I haven't talked about this underwear to my crew members," Wakata said in an interview with The Associated Press, drawing a big laugh from his six shuttle colleagues. "But I wore them for about a month, and my station crew members never complained for about a month, so I think the experiment went fine."
The Japanese underwear, called J-Wear, is a new type of anti-bacterial, water-absorbent, odor-eliminating clothing designed for space travel. The line includes shirts, pants and socks as well. Wakata tested all of them during his mission; he had four pairs of the silver-coated underwear, a cross between briefs and boxers.
"We'll see the results after landing," Wakata said.
J-Wear is billed as being antistatic and flame retardant, which is especially important for spaceship wear. The cotton and polyester clothes are also seamless, making them lighter and more comfortable, according to the Japanese Space Agency. The goal is "comfortable everyday clothes for life in a spaceship."
Another Japanese astronaut wore some J-Wear items during a shuttle flight last year, but had only 16 days in orbit to try them out.
NASA's space station program manager, Mike Suffredini, stressed the importance of testing new products, especially those aimed at improving astronauts' quality of life. There's no way to wash clothes in space. Station residents simply ditch dirty outfits, along with other garbage, in no longer needed cargo ships that are sent plunging in flames through the atmosphere.
"Eventually, we're going to do exploration. We're going to go to the moon. We're going to go beyond the moon someday, and little things like this will seem like really, really big things when you're far away from Mother Earth," Suffredini told reporters.
Good weather was forecast for Friday's late morning landing attempt, with the rain expected to hold off until afternoon at NASA's spaceport.
On Thursday afternoon, NASA cleared Endeavour to come home, after analyzing wing and nose images beamed down by the crew Wednesday in one final sweep for micrometeorite damage.
"I'm ready to get back ... I think I have a landing in me, so don't want to get anybody on the ground worried about that," commander Mark Polansky told the AP.
In one of NASA's longer shuttle flights, Polansky and his crew put a new addition onto the international space station - a porch for Japan's massive $1 billion lab - and freshened up the place with batteries, experiments and spare parts. They rocketed into space July 15.
Thursday marked Day 15 in space for Polansky and all but one of his crew. For Wakata, Thursday marked Day 137. He flew to the space station back in March, becoming the first person from Japan to live at the orbiting outpost.
Wakata said he's longing for sushi.
"That's the first thing that I'd like to have and also a hot spring in Japan sometime in the near future," Wakata told the AP.
Earlier in the day, the shuttle astronauts released a small canister containing a navigation and rendezvous experiment. Five hours later, the crew launched an atmospheric density experiment so scientists can better understand how orbiting objects move and eventually come down.
Over at the space station, meanwhile, the major air-purifying system on the U.S. side failed again, and the crew spent the day trying to fix the equipment. Engineers suspect a heating element is causing a short.
A carbon dioxide-removal system on the Russian side is still operating properly, and the six astronauts have backup methods for cleansing the cabin atmosphere. But the American system is critical for long-term space station operations. It overheated over the weekend and shut down, but flight controllers managed to work around the problem, at least for a few days.
As for NASA's next station visit, officials are targeting an Aug. 25 launch of Discovery, provided that a few remaining tests of the fuel tank shows the insulating foam is attached properly.
An unusually large amount of foam broke off Endeavour's fuel tank during liftoff. Deputy shuttle program manager LeRoy Cain said dust or other debris may have gotten on the tank and not been cleaned off prior to the foam application. Some of the workers may not have been familiar enough with the job, he noted.
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